The field of this invention relates to signaling devices, and more particularly to a signal device which is automatically activated by small pressure variations within the system in which the device is mounted.
The ultimate performance goal for any signaling device is to render an attention demanding signal consistently and without fall whenever prescribed by chosen conditions. In the past, in order to produce a reactive signal sensitive to pressure variations, a vortex resonator has been used. Such devices require high velocity fluid flow to produce signals and are not easily adaptable to the production of signals automatically. Further, the point at which the signal is generated in such devices is subject to wide variation due to overtone effects. The alternative to vortex resonators has been complicated mechanical devices involving vibrating reeds, balls, and the like, and involved the mechanical motion of one or more parts. Often these devices are subject to mechanical failure, are costly to make, and require substantial pressure variation for activation. On the other hand, non-mechanical devices designed to be reactive to small variations in pressure were incapable of producing a signal of sufficient energy to be of value in many applications.
As a result of these considerations, devices for automatic signaling of small pressure variations in the past have been at least partially inadequate to accomplish their designed purpose.
Therefore, it would be desirable to design an automatic signaling device which is sensitive to small pressure variation, and produces an effective signal without failure-prone mechanical mechanisms.